Keep doing that and you'll go blind

This article is a little old (from Feb) but I found it pretty useful. Kinda scary thinking that 3D technology might be a bad thing, especially for kids.

Virtual reality headsets use the same technique for displaying 3D as we find in movies or 3D television sets - parallax. They project a slightly different image to each one of your eyes, and from that difference, your brain creates the illusion of depth. That sounds fine, until you realize just how complicated human depth perception really is. The Wikipedia entry on depth perception (an excellent read) lists ten different cues that your brain uses to figure out exactly how far away something is. Parallax is just one of them. Since the various movie and television display technologies only offer parallax-based depth cues, your brain basically has to ignore several other cues while you're immersed in the world of Avatar. This is why the 3D of films doesn't feel quite right. Basically, you're fighting with your own brain, which is getting a bit confused. It's got some cues to give it a sense of depth, but it's missing others. Eventually your brain just starts ignoring the other cues.

That's the problem. When the movie's over, and you take your glasses off, your brain is still ignoring all those depth perception cues. It'll come back to normal, eventually. Some people will snap right back. In others, it might take a few hours. This condition, known as 'binocular dysphoria', is the price you pay for cheating your brain into believing the illusion of 3D. Until someone invents some other form of 3D projection (many have tried, no one has really succeeded), binocular dysphoria will be part of the experience.

This doesn't matter too much if you're going to see a movie in the theatre - though it could lead to a few prangs in the parking lot afterward - but it does matter hugely if it's something you'll be exposed to for hours a day, every day, via your television set. Your brain is likely to become so confused about depth cues that you'll be suffering from a persistent form of binocular dysphoria. That's what the testers told Sega, and that's why the Sega VR system - which had been announced with great fanfare - never made it to market.

Video games are one of the great distractions of youth. Children can play them for hours every day, and our testers realized that children - with their highly malleable nervous systems - could potentially suffer permanent damage from regular and extensive exposure to a system which created binocular dysphoria in its users. This is the heart of my concern, because 3D television is being pitched as an educational medium - Discovery Channel has announced 3D broadcasts will begin mid-year - and that medium could damage the growing minds it is intended to enlighten.